Patent literature 1 discloses a signal indicator light formed in a columnar shape which is long in a vertical direction. The signal indicator light includes a plurality of indicator units arranged along the vertical direction and a sound notification unit. An opening portion is formed in a side surface of a cylindrical case of the sound notification unit. A cylindrical portion extending in a horizontal direction is directed inside of the cylindrical case in the opening portion. A lid with an amplification throat portion is attached to this cylindrical portion. A communicating hole is formed vertically downward on an upper portion of an inner wall surface of the cylindrical portion. At an upper side of the communicating hole in the cylindrical case, a sound source installation portion which is a space for housing a speaker and its mounting substrate is formed. Sound waves generated from the speaker advance from the communicating hole to the amplification throat portion and diffuse from the opening portion toward the outside of the sound notification unit.
Patent literature 2 discloses an electric device including a housing with a substantially annular mounting portion for mounting a piezoelectric sounder on an inner surface of the housing. A sound emission hole penetrating the housing is formed at a substantially central position of the mounting portion. A piezoelectric vibrating plate constituting a piezoelectric sounder is attached to the mounting portion via an annular spacer. An empty chamber is formed by the piezoelectric vibrating plate, the spacer, the mounting portion, and the housing. Sound emitted by the piezoelectric vibrating plate is resonated in the empty chamber and is transmitted to the outside from the sound emission hole.